Water jacketed exhaust relief system

ABSTRACT

Disclosed herein is a marine propulsion device comprising a propulsion unit including a lower unit rotatably supporting a propeller and intended to be at least partially submerged in water, together with an internal combustion engine including an exhaust gas outlet, an exhaust discharge outlet located in the lower unit and intended to be submerged in water when the engine is operating at low speed, an exhaust gas duct communicating between the engine exhaust gas outlet and the underwater discharge outlet, an exhaust relief outlet communicating with the atmosphere, and a conduit communicating between the exhaust gas duct and the exhaust relief outlet, and a water jacket extending around the conduit from adjacent to the exhaust gas duct to adjacent the atmosphere.

United States Patent Miller et al. Oct. 14, 1975 [54] WATER JACKETED EXHAUST RELIEF 3,577,952 5/1971 Tado 115/17 SYSTEM Primary ExaminerTrygve M. Blix [75 Inventors g r l r w i b h Assistant Examiner-Charles E. Frankfort O f n l egan 0t Attorney, Agent, or Firm-Michael, Best & Friedrich [73] Assignee: Outboard Marine Corporation, ABSTRACT Waukegan, lll. Disclosed herein is a marine propulsion device com- [22] Filed, Feb 20 1974 prising a propulsion unit including a lower unit rotatably supporting a propeller and intended to be at least [21] Appl. No: 444,050 partially submerged in water, together with an internal 12?} li'fi'il' :3:1:3:i:1:::1:1:3::3:13:1:13iiiiffi llafikfi ineewled to be submerged in weer when the engine 1 58 Field of Search 115/17, 18 R, 0.5 R, 34 R opiimtmg Speed f exhaust gas duct commun catmg between the engine exhaust gas outlet and the [56] References Cited underwater discharge outlet, an exhaust relief outlet communicating with the atmosphere, and a conduit UNITED STATES PATENTS e communicating between the exhaust gas duct and the Johnson R exhaust relief utlet and a water jacket extending 2935939 5/1960 Thompson 115/05 R around the conduit from adjacent to the exhaust gas 3331 11353 Z1132? Eilfiifiiiiii.......... 13:13:31 112113 duct to adjacent the atmosphere- 3,434,447 3/1969 Christensen et al. 115/05 R 6 Claims, 2 Drawing Figures combustion engine including an exhaust gas outlet, an exhaust discharge outlet located in the lower unit and U.S. Patent Oct. 14, 1975 P WW V Q Q WN I a m WATER JACKETED EXHAUST RELIEF SYSTEM BACKGROUND OF THE INVENTION The invention relates generally to marine propulsion devices, such as outboard motors and stern drive units and, more particularly, to exhaust gas discharge systems. Still more particularly, the invention relates to exhaust gas relief arrangements or systems.

In the past, it has been common for marine propulsion devices to discharge their exhaust into the water. However, when idling without forward motion or when operating at relatively low speeds, the water surrounding the underwater exhaust gas discharge outlet can effectively block exhaust gas discharge. As a consequence, an exhaust relief, operable at idle and low speed conditions, has been provided to permit exhaust discharge directly to the atmosphere and not through the water. In some prior constructions, water was introduced into the exhaust gas to cool the gases, including the gas exiting from the exhaust relief arrangement. In other exhaust relief arrangements, the various.components defining the relief. arrangement was left uncooled.

Examples of prior constructions embodying exhaust reliefs are found in the Hulsebus U.S. Pat. No. 3,045,423, issued July 24, 1962, and in the Larsen U.S. Pat. No. 3,198,162 issued Aug. 3, 1965.

Attention is also directed to the Miller U.S. Pat. No. 3,520,270 issued July 14, 1970 and to the Boerma U.S. Pat. No. 3,695,238 issued Oct. 3, 1972.

SUMMARY OF THE INVENTION The invention provides a marine propulsion device comprising a propulsion unit including a lower unit rotatably supporting a propeller and intended to be at least partially submerged in water, together with an internal combustion engine including an exhaust gas outlet, an exhaust gas discharge outlet located in the lower unit and intended to be submerged in water when the engine is operating at low speed, an exhaust gas duct communicating between the engine exhaust gas outlet and the underwater exhaust gas discharge outlet, an exhaust relief outlet communicating with the atmosphere, an exhaust conduit communicating between the exhaust gas duct and the exhaust relief outlet, and a water jacket extending around the exhaust relief conduit from adjacent the exhaust gas duct to adjacent the atmosphere.

In further accordance with the invention, the water jacket extending around the exhaust relief conduit is a part of a larger water jacket surrounding the exhaust gas duct extending between the engine exhaust outlet and the underwater exhaust discharge outlet. In addition, the water jacket around the exhaust relief conduit can communicate with a discharge opening located adjacent the exhaust relief outlet.

One of the principal features of the invention is the provision or a water jacketed exhaust relief conduit which communicates with an exhaust relief outlet and which affords exhaust relief when the engine is operating at low or idling speeds.

Another of the principal features of the invention is the provision of an above water-level water discharge to the atmosphere from a water jacket surrounding an exhaust relief conduit. 1

Another of the principal features of the invention-is the provision of an exhaust relief system which avoids mixture of water with the exhaust gases exiting through the exhaust relief system.

Other features and advantages of the invention will become known by reference to the following drawings, general description, and claims.

THE DRAWINGS FIG. 1 is a side elevational view, partially broken ,away and in section, of one embodiment of a marine propulsion device embodying various of the features of the invention.

FIG. 2 is a side elevational view, partially broken away and in section, of a second embodiment of a marine propulsion device embodying various of the features of the invention.

Before explaining the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts set forth in the following general description or illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

GENERAL DESCRIPTION Shown in FIG. 1 of the drawings is a marine propulsion device in the form of an outboard motor 11 which includes a propulsion unit 13 and means adapted for attaching the propulsion unit 13 to the stern of a boat and for permitting horizontal swinging or steering movement and vertical tilting'movement of the propulsion unit 13 relative to the boat. Any suitable attaching arrangement can be employed.

Also included in the propulsion unit 13 are a lower unit 17 and a powerhead 21. The lower unit 17 includes a gear box 23 which supports a propeller 25 and which can include a reversing transmission 27, together with a drive shaft housing 29 which is fixed to the gear box 23 and extends upwardly therefrom. The powerhead 21 includes an internal combustion engine 31 which is rigidly mounted relative to the lower unit 17 on the drive shaft housing 29 and which includes an exhaust gas outlet 33.

The invention is not limited to any particular type of I internal combustion engine, and the invention is not limited to either an outboard motor or to an outboard motor including a drive shaft housing. Furthermore, the reversing mechanism forms no part ofthe present invention.

Also included in the lower unit 17 is an exhaust gas discharge outlet 41 which, as illustrated, is of the through-the-propeller type. Other exhaust gas discharge outlets can also be employed. The exhaust gas discharge outlet can either be underwater at all times or can be located so that it is elevated above the water line during high speed operation when the supporting boat rises up on a plane.

Extending in the lower unit 17 between the engine exhaust gas outlet 33 and the exhaust gas discharge outlet 41 is a main exhaust gas duct 43 which, at least in part, is provided with a water jacket 45 defined by suitable wall means 47. (Water can be supplied to the waterjacket 45 from the cooling water discharged from the engine 31 or by any other suitable means.)

While other arrangements could be employed, in the illustrated construction, the wall means 47 includes an overflow edge or weir 49 which conducts overflow or discharge water for passage through a port 51 in the outer wall of the lower unit, and into the atmosphere. If desired, the overflow water discharge could be ducted internally of the drive shaft housing 29 for discharge from the lower unit 17 directly into the water below the normal operating water level, or for discharge into a lower part of the exhaust gas duct 43 for mixture with the exhaust gas. Alternatively, the water jacket 45 could extend continuously upwardly (as shown in FIG. 2) to the engine 31, and a restricted opening (not shown) could be provided adjacent to the bottom of the water jacket 45 for discharge of the water into the atmosphere, or directly into the water below the normal operating water level, or into the exhaust gas duct 43. The size of the restricted opening would be such, as compared to the capacity of the water pump (not shown), so that, in operation, the water jacket would be substantially full whenever the engine is running.

As underwater exhaust gas discharge is often blocked or prevented, when the outboard motor is idling or operating at low speeds, by the mass of the water at the exhaust gas discharge outlet, an exhaust gas relief means is provided. In the illustrated construction, such exhaust relief means comprises an exhaust gas relief outlet or port 61 which is located in an outer wall of the propulsion unit 13 and, more specifically, is located in the lower unit 17 and communicates with the atmosphere. More specifically, in the illustrated construction, the exhaust relief outlet or port 61 is located in the drive shaft housing 29. In addition, there is provided an exhaust relief conduit 63 which extends between the exhaust relief outlet 61 and the exhaust gas duct 43.

in further accordance with the invention, there is also provided a water jacket 71 which surrounds the exhaust relief conduit 63 and which extends for the full length of the exhaust relief conduit 63 to adjacent to the lower unit outer wall in which the exhaustrelief outlet or port 61 is provided. In the illustrated construction, the water jacket 71 surrounding the exhaust relief conduit 63 forms a part of, or communicates with, the previously described water jacket 45. it is noted that, in the disclosed construction, there is no mixing of water with the exhaust gas in the exhaust relief conduit and that there is no mixing of water with the exhaust gas in that portion of the exhaust gas duct 43 above the exhaust relief conduit. if desired, mixture of water with the exhaust gases can be completely prevented while still adequately cooling the exhaust gas system.

Shown in FlG. 2 is another marine propulsion device which embodies various of the features of the invention and which is in the form of an outboard motor 111 and which, except as noted hereafter, can be constructed in the same fashion as the outboard motor 111 shown in HO. 1. Accordingly, the same reference numerals have been applied in FlG. 2 as have been applied to the corresponding components or portions of FIG. 1.

In the FIG. 2 embodiment, the wall means 47 defining the water jacket 45 surrounding the exhaust gas duct 43 extend continuously up to the engine 31 so that the water jacket 45 extends continuously from the engine 31.

As in the FIG. 1 construction, there is also provided an exhaust relief outlet 61, and an exhaust relief conduit 63 communicating between the exhaust relief outlet 6] and the exhaust gas duct 43. As also in the FIG. 1 embodiment, there is provided a water jacket 71 which surrounds the exhaust relief conduit 63 and which forms a part of the water jacket 45. However, as distinguished from the FlG. 1 embodiment. the water jacket 71 surrounding the exhaust relief conduit 63 communicates with a discharge opening located in the outer wall of the lower unit 17. More specifically, in the illustrated construction, the discharge opening 175 is located in the drive shaft housing and extends at least partially circumferentially of the exhaust relief outlet 61. As already indicated. the discharge opening 175 can be sized relative to the water pump (not shown) so as to maintain the water jacket 45 substantially full of water when the engine is running.

Discharge water from the cooling jacket 71 of the FIG. 2 embodiment flows around the exhaust relief conduit 63 and outwardly of the lower unit 17 through the discharge opening 175 in a spray or stream adjacent to the exhaust relief outlet 61. However, as already indicated, when the outboard motor 11 or 111 is moving at speeds above low speed, exhaust gas discharge nor- 'mally takes place through the exhaust gas discharge outlet 41.

Various of the features of the invention are set forth in the following claims.

What is claimed is: i

1. A marine propulsion device comprising a propulsion unit including a lower unit rotatably supporting a propeller and intended to be at least partially submerged in water, an internal combustion engine including an exhaust gas outlet, an exhaust gas discharge outlet located in said lower unit and intended to be submerged in water when said engine is operating at low speed, an exhaust gas duct extending from said engine exhaust gas outlet to said discharge outlet, an exhaust relief outlet communicating with the atmosphere, an exhaust relief conduit extending from said exhaust gas duct to said exhaust relief outlet, and a water jacket extending around said exhaust relief conduit from said exhaust gas duct to said exhaust relief outlet.

2. A marine, propulsion device in accordance with claim 1 wherein said water jacket includes a discharge opening located adjacent to said exhaust relief outlet.

3. A marine propulsion device in accordance with claim 1 wherein said water jacket communicates with a water jacket surrounding at least a part of said exhaust gas duct.

4. A marine propulsion device in accordance with claim 3 wherein said water jacket extending around said exhaust relief conduit includes a discharge opening extending partially circumferentially of said exhaust relief outlet.

5. A marine propulsion device in accordance with claim 1 wherein said engine is rigidly connected to said lower unit.

6. A marine propulsion device in accordance with claim 1 wherein said lower unit includes a gear box and a drive shaft housing rigidly connected to and located between said gear box and said engine, wherein said exhaust gas duct is partially located in said drive shaft housing, and wherein said exhaust relief outlet constitutes an aperture in said drive shaft housing. 

1. A marine propulsion device comprising a propulsion unit including a lower unit rotatably supporting a propeller and intended to be at least partially submerged in water, an internal combustion engine including an exhaust gas outlet, an exhaust gas discharge outlet located in said lower unit and intended to be submerged in water when said engine is operating at low speed, an exhaust gas duct extending from said engine exhaust gas outlet to said discharge outlet, an exhaust relief outlet communicating with the atmosphere, an exhaust relief conduit extending from said exhaust gas duct to said exhaust relief outlet, and a water jacket extending around said exhaust relief conduit from said exhaust gas duct to said exhaust relief outlet.
 2. A marine propulsion device in accordance with claim 1 wherein said water jacket includes a discharge opening located adjacent to said exhaust relief outlet.
 3. A marine propulsion device in accordance with claim 1 wherein said water jacket communicates with a water jacket surrounding at least a part of said exhaust gas duct.
 4. A marine propulsion device in accordance with claim 3 wherein said water jacket extending around said exhaust relief conduit includes a discharge opening extending partially circumferentially of said exhaust relief outlet.
 5. A marine propulsion device in accordance with claim 1 wherein said engine is rigidly connected to said lower unit.
 6. A marine propulsion device in accordance with claim 1 wherein said lower unit includes a gear box and a drive shaft housing rigidly connected to and located between said gear box and said engine, wherein said exhaust gas duct is partially located in said drive shaft housing, and wherein said exhaust relief outlet constitutes an aperture in said drive shaft housing. 